Effect of temper, specimen orientation and test temperature on the tensile and fatigue properties of SiC particles reinforced PM 6061 Al alloy

The room temperature stiffness and strength of 6061 Al alloy fabricated by powder metallurgy (PM) are markedly improved by SiC reinforcement but such beneficial effects are lost at 300 °C. The fatigue crack growth resistance is in general improved by over-aging, the LT orientation and SiC reinforcement but decreased by rising temperature. As the fracture toughness decreases with increasing amount of reinforcement, the unreinforced alloy exhibited better crack growth resistance than the reinforced composites for growth rates greater than 5 × 10−4 mm/cycle at all temperatures. The difference in growth resistance is discussed in terms of the microstructural and fractographic evidences.